Mad cow disease has been confirmed in the U.S., but what is the real effect on your day-to-day diet? Are there options for buying "safer" meat? Should we even be worried at all? We learned the answers when we welcomed Ellen Haas, CEO of foodfit.com and former USDA official, to WebMD Live.

The opinions expressed herein are the guest's alone and have not been reviewed by a WebMD physician. If you have questions about your health, you should consult your personal physician. This event is meant for informational purposes only.

Moderator: Welcome, Ellen. Mad cow disease has finally come to the U.S. -- by way of Canada, it seems. But I don't see McDonald's closing down or people buying out tofu supplies in the grocery. Is it really business as usual for American meat eaters?

Haas: I think the situation for meat eating has shifted a bit. I think that consumers are cautiously concerned, but they haven't thrown their love of steak or hamburger out the window. As consumers received more information and the government, meaning the Department of Agriculture, began to respond with new regulations, consumers got more comfortable with buying beef, however still had questions about what all this means, as they should.

Member question: Can you tell me what is exactly the infectious agent with this disease? It infects the nervous system through ingesting infected tissue, but is it a bacteria, virus, etc., or what?

Haas: Mad cow disease is the common name for a progressive neurological disorder of cattle, also known as bovine spongiform encephalopathy. It's caused by abnormal proteins called prions that bore sponge-like holes in the brain and eventually destroyed it. Prions have become, you might say, the consumer alert of the season, All of a sudden people are hearing this word the first time and it's quickly becoming a household word.

The cases in England are very, very troubling in that the road that people have to travel when they get sick is very disconcerting; it couldn't be much worse. It's a deterioration of your mind and body. It's a very serious disease, and though it's very rare it causes great concern.

The cattle contract the disease by eating the recycled remains of other BSE infected animals. Once it gets into the system it can appear again, and that is another reason for concern and for necessary government action.

In 1997 the United States Department of Agriculture did ban the use of ground up ruminants (cattle, goats, sheep, and deer) in cattle feed. The reason for this is when an animal does get BSE the prions are found in the brain, spinal cord, eyes, lymph nodes, marrow, and spleen, so it's of utmost importance that these ruminants not be recycled, so to speak, in the feed of other cattle, because that is how the disease is passed along. Eventually, as it's passed from cattle to cattle it could be passed to humans unless the necessary protections in food are in place.

Member question: Are cows the only meat-producing animal that carry this? Is there any chance of it 'jumping' to pigs or chickens?

Haas: If they are fed the animal feed that is contaminated, then they can also get sick. The problem lies in the contaminated animal feed and the kind of protections we have about ensuring that the animal feed is wholesome, and making sure that the cattle that are sick are not slaughtered for human use.

Member question: I was really surprised to learn than "downer" cows were used for human consumption. Why would they allow sick appearing animals into the food chain?

Haas: That's a very good question. It's probably in that case that economic interests outweighed health interests, and that when the cattle industry is hurting and there are those who can sell a product, albeit a damaged one, then the marketplace gets a price for it. If someone can sell something in an open marketplace, then they will.

It's very important, therefore, that downer cattle be prohibited from being sold. The action taken by USDA on December 30 prohibiting cattle that are downers from being slaughtered for human consumption was something long past due. We should have had that prohibition in place for a long time in our food safety system.

Member question: I read that although the brain and spinal column are removed, the spinal ganglia are not. Then the bones are pressed to extract every last bit of marrow, meat, etc. What's the point of saying the meat supply is safe if these kinds of extraction methods are used?

Haas: For more than a decade we've had new processing techniques called advanced meat recovery that are so advanced in their ability to capture all the meat on a carcass and ground it up they also have included the nervous system tissue connected to the spinal cord, which is called dorsal root ganglia. The new regulations of USDA just issued do prohibit it; however, AMR has been a system that has really been under-regulated, and so consumers need to be aware there is little enforcement of this process.